feat(ios): Turn on debug view for debug builds

[MaximBelov]

https://firebase.google.com/docs/analytics/debugview

https://github.com/firebase/firebase-ios-sdk/blob/e8c71d1f7f3363b488f9f2045845afbb82fd016a/FirebaseCore/Sources/FIRLogger.m#L75

firebase/firebase-ios-sdk#13640 (comment)

PR Type

What kind of change does this PR introduce?

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Documentation changes
• Other... Please describe:

PR Checklist

Please check your PR fulfills the following requirements:

Bugfixes:

• Regression testing has been carried out using the example project to ensure the intended bug is fixed and no regression bugs have been inadvertently introduced.

New features/enhancements:

• Exhaustive testing has been carried out for the new functionality
• Regression testing has been carried out to ensure no existing functionality is adversely affected
• Documentation has been added / updated
• The example project has been update to validate/demonstrate the new functionality.

What is the purpose of this PR?

Does this PR introduce a breaking change?

• Yes
• No

What testing has been done on the changes in the PR?

What testing has been done on existing functionality?

Other information